The present invention relates to polymer optical waveguides disposed on polymer substrates, and more specifically, to perfluorinated polymer optical waveguides.
Optical waveguides can be formed in polymers by using a core polymer and a cladding polymer with the core polymer refractive index slightly higher than that of the cladding polymer in the near infrared region of the third optical telecommunication wavelength window (around 1550 nm). In order to form useful optical waveguide devices such as integrated splitters, couplers, arrayed waveguide gratings, and optical waveguide amplifiers, it is essential to have stable and low loss optical waveguides. The optical loss, or attenuation of an optical waveguide, originates primarily from two sources: 1) optical absorption and scattering by the core and cladding material themselves and 2) optical signal scattering due to imperfections of the waveguide structure, such as wall roughness.
A general approach for making planar polymer optical waveguides is to dispose an undercladding polymer film layer on a substrate and then a polymer core film layer on top of the undercladding layer. The polymer core layer film subsequently undergoes metallization, lithography and etching processes from which a rectangular cross-section channel is formed. An overcladding polymer film layer is then disposed on top of the waveguide core and the exposed undercladding film layer.
It is well know that, by adding rare earth elements, such as erbium, to a polymer core in an optical waveguide, and by exciting the waveguide with a pump light, the waveguide can act as an optical amplifier, amplifying a light signal being transmitted through the waveguide, allowing the light signal to be transmitted over great distances.
However, it has been found that, when adding the rare earth element, particularly erbium, to the core polymer, adhesion between the core and the cladding layers that surround the core is greatly reduced, whereby the core tends to delaminate from the cladding layers, reducing the effectiveness of the waveguide to transmit light. It would be beneficial to provide a waveguide in which the rare earth containing core properly adheres to the surrounding cladding layers.
Briefly, the present invention provides a waveguide optical amplifier. The waveguide optical amplifier comprises a generally planar substrate and a lower cladding disposed on the substrate. A first barrier is disposed on the lower cladding and a core is disposed on at least a portion of the first barrier.